Re: Trees in SQL

Check mailing list archive and try
http://www.sai.msu.su/~megera/postgres/gist/tree/
You'd need tree.tar.gz and test data to play with (dmoz catalog)
Unfortunately there is no doc in english :-(
Our approach is extremely fast for searching.

Oleg

On Fri, 24 May 2002, Gregory Brauer wrote:

>
> I hope this isn't an overly broad topic that ends up diverging into graph
> theory, but I have a tree structure of identical items (analogous to a
> filesystem directory tree) that I need to store in Postgres. The
> "obvious" design is to give the table that will represent these objects
> a field identifying its "parent" that is a relation to the same table.
> However, this seems to make many common SQL queries rather difficult.
>
> What sort of strategies are best for storing tree structures in a
> relational database, and how would one structure SQL queries to find,
> say, "all of the children anywhere under this node", or to represent
> the condition "if this node is a child at any depth under this other
> node"? Are there good strategies for preventing cycles?
>
> I'd appreciate any insights anyone can give.
>
> Thanks.
>
> Greg Brauer
> greg(at)wildbrain(dot)com
>
>
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Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83